Boss 302 Bolt-On Upgrades - Haul Natural

Bolting on big Boss 302 performance improvements without a power adder

KJ JonesBrand Manager, 5.0 Mustang & Super Fords

April 15, 2014

12. Intake and exhaust cams are specific to each side of the engine. After preparing both camshaft packages with their correct phasers, cam gears, chains, and tensioners, Eddie drops each cam set onto the Roadrunner engine.

13a-b. Once the cams are secured on each cylinder head, the stock timing chains, guides, tensioners, cam covers and TiVCT solenoids are all reinstalled, along with the front cover.

14. Ford Racing Performance Parts’ Cobra Jet intake manifold is the primary air-induction change that we’re making with this project. The composite CJ manifold is the same intake Ford Racing created for its naturally aspirated, 5.0-powered (race-only) ‘13 Cobra Jet ‘Stangs. It’s a direct replacement for the factory Boss 302 intake. Previous tests have shown the Cobra Jet manifold’s optimized runners and voluminous plenum area help promote significant high rpm power increases, without experiencing the torque drop that might be expected from a short-runner manifold. Notice, stock fuel rails are retained with the CJ intake, and we found the OEM strut-tower brace actually can be reinstalled with this manifold.

15. An FRPP twin-bore (65mm) Cobra Jet throttle body (PN M-9926-CJ65) is the second major air-intake component we’re adding. The billet throttle body actually is required equipment for the CJ intake, and installs with basic tools and requires one wiring procedure; linking a jumper harness with the Boss’s original throttle-body harness, which must be repinned into a connector that’s included with the throttle body.

16. While all precautions were taken to keep debris out of the oil pan while the engine’s front dress was off, it’s best to err on the side of caution and perform an oil service. Like their Coyote siblings, Roadrunner 5.0s use 5W-50 synthetic oil.

17. At the time of our test, the crew at Power by the Hour were the only folks making a cold-air-induction system that supports the Cobra Jet intake/throttle body swap on ’11-up Mustang GTs and ’12-’13 Boss 302. The simple kit features everything you see here, highlighted by a massive, oval-shaped, 4.5-inch aluminum intake pipe (with mass air flange and PCV bung incorporated in it), an ABS plastic heatshield, stainless-steel T-bolt clamps, and an S&B conical air filter.

18. The CAI install is straightforward. Tony completed the task using handtools.

19. Having already tested Ford Racing’s Cobra Jet intake, throttle body, and Power by the Hour’s CAI package on a Boss 302 in a past tech project (Sept. ’13) and noting its impact on the ‘Stang’s performance, we were really interested in seeing how only the headers would affect a Boss. After installing the Dynatechs, Eddie strapped our test Pony down on the Dynojet chassis dyno for a few pulls. It’s important to note that tuning is required with this type of upgrade. Eddie uses SCT’s Advantage III tuning software for all of the engine-related upgrades that Addiction Motorsports performs on Coyote, Roadrunner, and Trinity powerplants.

On the Dyno

Let us start by saying this: We haven’t ever heard anything sound as evil as a naturally aspirated Roadrunner engine screaming its way to 8,000 rpm on the chassis dyno. Yes, the hopped-up bullet in Tony Napolitano’s ’13 Boss 302 is now capable of stretching out to eight grand, and makes power almost all the way up to that peak rev limit.

In a slight twist of installation protocol, we installed Dynatech’s SuperMaxx long-tube headers first, to evaluate their impact on the Boss’s stock engine. The Roadrunner is inherently stout and breathes well on the intake side. As the data shows, improving a Boss 302’s exhaust with long-tubes, as opposed to the basic after-cat system, brought about instant, across-the-board increases in power and torque. We note these stats up front because we understand budgets may not support going all-in with an upgrade package like this. Headers are a fine, standalone mod that will keep you content until the bigger surgeries are in the budget.

Photo Gallery

The cams, intake, throttle body, and Power by the Hour induction package is identified as Top I in our dyno chart, and is (along with the exhaust data) the primary baseline-to-bolt-ons comparison set for our test. After recording results for this group, we performed a bonus test on a prototype version of Ford Racing Performance Parts’ cold-air upgrade for the CJ intake (Top II). While both induction groups are effective, the difference in where gains are achieved is intriguing, and Eddie believes the difference in the cold-air tubes’ design makes this so.

“I knew that the tuning required for both cold-air kits would be different,” Eddie said. “The Power by the Hour tube is huge, and as such allows for more aggressive timing and fueling, which made significant power in the 6,800-to-8,000-rpm range. By contrast, though, the Ford Racing prototype piece works well in the lower revs (2,700-5,700) and probably would be the more-street-friendly option, as torque with the FRPP piece is about the same.”